Major, minor and patch represent the different releases of a package.
npm uses the tilde (~) and caret (^) to designate which patch and minor versions to use respectively.
So if you see ~1.0.2 it means to install version 1.0.2 or the latest patch version such as 1.0.4. If you see ^1.0.2 it means to install version 1.0.2 or the latest minor or patch version such as 1.1.0.